x = int(input())
y = int(input())
l = int(input())
count = 0

if x != 0:
    count += (abs(x) + l - 1) // l
if y != 0:
    count += (abs(y) + l - 1) // l

if (x != 0) and ('-' in str(y) ):
    count += 2
elif x != 0:
    count += 1
elif '-' in str(y):
    count += 2
    
print(count)